1. Field of the Invention
The present invention is concerned with a novel process for the manufacture of heterocyclic compounds, which are suitable as intermediates for the manufacture of D-(+)-biotin, as well as a process for the manufacture of D-(+)-biotin itself. The invention is also concerned with novel intermediates in this process.
2. Background Description
D-(+)-Biotin is a substance which has been known for a long time and a number of processes for its manufacture are also already known. The necessity of attaching the carboxybutyl side chain to the ring system at some stage is common to the technically interesting processes. Various solutions are known for this such as, for example, the synthesis of the side chain according to the coupling scheme C.sub.4 +C.sub.1 .fwdarw.C.sub.5 or also C.sub.3 +(C.sub.3 -C.sub.1 =C.sub.2).fwdarw.C.sub.5. It is also known to attach the side chain to the ring system in one step by means of a Wittig reaction. However, all of these processes have the disadvantage that they either proceed via a relatively large number of reaction steps or require a relatively large expenditure for the isolation of the desired end product.
There accordingly exists a need for a technically simple process in which the side chain can be attached to the ring system in good yield and in as far as possible one reaction step. This is now possible by means of the process of the invention.